Recent developments in communication technology have led to the introduction of mobile digital communication devices that provide several different types of service. As a result, modern communication devices may be faced with the task of receiving and processing a variety of different types of signals. This flexibility may provide significant design challenges when combined with the space and power restrictions associated with mobile devices.
In particular, receivers that can tune across multiple sub-bands of the radio-frequency spectrum, including sub-bands of different sizes, can be difficult to design. Designing a receiver to accept signals within multiple sub-bands of varying sizes may compromise the receiver's performance when receiving signals in some or all of the sub-bands. Both linearity and noise characteristics may be sacrificed to provide frequency flexibility. Furthermore, the power limitations faced by mobile devices result in headroom requirements for such devices that create additional design challenges.